%0 Journal Article %T A secondary Chern-Euler class %A Ji-Ping Sha %J Mathematics %D 1999 %I arXiv %X Let xi be a smooth oriented vector bundle, with n-dimensional fibre, over a smooth manifold M. Denote by xi-hat the fibrewise one-point compactification of xi. The main purpose of this paper is to define geometrically a canonical element Upsilon(xi) in H^n(xi-hat,Q) (H^n(xi-hat,Z) tensor 1/2, to be more precise). The element \Upsilon(\xi) is a secondary characteristic class to the Euler class in the fashion of Chern-Simons. %U http://arxiv.org/abs/math/9911269v1